 /*******************************************************************************
  * Copyright (c) 2007 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  ******************************************************************************/

 package org.eclipse.ui.internal.menus;

 import java.util.ArrayList ;
 import java.util.Collection ;
 import java.util.Iterator ;
 import java.util.List ;

 import org.eclipse.core.expressions.Expression;
 import org.eclipse.jface.action.IContributionItem;
 import org.eclipse.ui.internal.expressions.AlwaysEnabledExpression;
 import org.eclipse.ui.menus.IContributionRoot;

 /**
  * Default implementation.
  *
  * @since 3.3
  */
 final class ContributionRoot implements
         IContributionRoot {

     private List topLevelItems = new ArrayList ();
     private List itemsToExpressions = new ArrayList ();
     private InternalMenuService menuService;
     private Expression restriction;
     private String namespace;

     public ContributionRoot(InternalMenuService menuService, Expression restriction, String namespace) {
         this.menuService = menuService;
         this.restriction = restriction;
         this.namespace = namespace;
     }

     /* (non-Javadoc)
      * @see org.eclipse.ui.menus.IContributionRoot#addContributionItem(org.eclipse.jface.action.IContributionItem, org.eclipse.core.expressions.Expression, org.eclipse.core.expressions.Expression)
      */
     public void addContributionItem(IContributionItem item,
             Expression visibleWhen) {
         if (item == null)
             throw new IllegalArgumentException ();
         topLevelItems.add(item);
         if (visibleWhen == null)
             visibleWhen = AlwaysEnabledExpression.INSTANCE;
         
         menuService.registerVisibleWhen(item, visibleWhen, restriction,
                 createIdentifierId(item));
         itemsToExpressions.add(item);
     }

     /**
      * Create the activity identifier for this contribution item.
      *
      * @param item the item
      * @return the identifier
      */
     private String createIdentifierId(IContributionItem item) {
         String identifierID = namespace != null ? namespace + '/'
                 + item.getId() : null; // create the activity identifier ID. If
 // this factory doesn't have a namespace
 // it will be null.
 return identifierID;
     }

     public Collection getItems() {
         return topLevelItems;
     }

     /**
      * Unregister all visible when expressions from the menu service.
      */
     public void release() {
         for (Iterator itemIter = itemsToExpressions.iterator(); itemIter.hasNext();) {
             IContributionItem item = (IContributionItem) itemIter.next();
             menuService.unregisterVisibleWhen(item);
         }
     }

     /*
      * (non-Javadoc)
      *
      * @see org.eclipse.ui.menus.IContributionRoot#registerVisibilityForChild(org.eclipse.jface.action.IContributionItem,
      * org.eclipse.core.expressions.Expression,
      * org.eclipse.core.expressions.Expression)
      */
     public void registerVisibilityForChild(IContributionItem item,
             Expression visibleWhen) {
         if (item == null)
             throw new IllegalArgumentException ();
         if (visibleWhen == null)
             visibleWhen = AlwaysEnabledExpression.INSTANCE;
         menuService.registerVisibleWhen(item, visibleWhen, restriction,
                 createIdentifierId(item));
         itemsToExpressions.add(item);
     }
 }

